Diamond cutting
Encyclopedia
Diamond cutting is the art, skill and, increasingly, science of changing a diamond
from a rough stone into a facet
ed gem. Cutting diamond requires specialized knowledge, tools, equipment, and techniques because of its extreme difficulty.
The first guild of diamond cutters and polishers (diamantaire) was formed in 1375 in Nuremberg
, Germany
, and led to the development of various types of 'Cut'. This has two meanings in relation to diamonds. The first is the shape: square, oval, and so on. The second relates to the specific quality of cut within the shape, and the quality and price will vary greatly based on the cut quality. Since diamonds are very hard to cut, special diamond-bladed edges are used to cut them. The first major development in diamond cutting came with the "Point Cut" during the later half of the 14th century: the Point Cut follows the natural shape of an octahedral raw diamond crystal, eliminating some waste in the cutting process.
Diamond cutting, as well as overall processing, is concentrated in a few cities around the world: while 80% of rough diamonds are handled in the Antwerp diamond district
in Belgium
, more than 50% of processed diamonds also pass through there. 92% of diamond pieces are cut in Surat
, Gujarat state in India. The other important diamond centers are Tel Aviv
and New York city
.
for the piece of diamond rough. The second is how quickly the finished diamond can be sold. Scanning devices are used to get 3-dimensional computer model of the rough stone. Also, inclusions are photographed and placed on the 3D model, which is then used to find an optimal way to cut the stone.
The weight retention analysis studies the diamond rough to find the best combination of finished stones as it relates to per carat value. For instance, a 2.20 carat (440 mg) octahedron may produce (i) either two half carat (100 mg) diamonds whose combined value may be higher than that of (ii) a 0.80 carat (160 mg) diamond + 0.30 carat (60 mg) diamond that could be cut from the same rough diamond.
The round brilliant cut and square brilliant cuts are preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals, such as macle
s are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight, about 50%. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the weight. Since the per-carat price of a diamond shifts around key milestones (such as 1.00 carat), many one-carat (200 mg) diamonds are the result of compromising Cut quality for Carat weight. Some jewelry experts advise consumers to buy a 0.99 carat (198 mg) diamond for its better price or buy a 1.10 carat (220 mg) diamond for its better cut, avoiding a 1.00 carat (200 mg) diamond, which is more likely to be a poorly cut stone.
In colored diamonds, cutting can influence the color grade of the diamond, thereby raising its value. Certain cut shapes are used to intensify the color of the diamond. The radiant cut is an example of this type of cut.
Natural green color diamonds most often have merely a surface coloration caused by natural irradiation, which does not extend through the stone. For this reason green diamonds are cut with significant portions of the original rough diamond's surface (naturals) left on the finished gem. It is these naturals that provide the color to the diamond.
Sawing is the use of a diamond saw or laser to cut the diamond rough into separate pieces.
of diamond
varies widely according to the direction in which one is trying to cut or grind.
A simplified round brilliant cut
process includes the following stages:
This is just one, although a fairly common way of creating a round brilliant cut. The actual process also includes many more stages depending on the size and quality of the rough stone. For example, bigger stones are first scanned to get the three-dimensional shape, which is then used to find the optimal usage. The scanning may be repeated after each stage and bruting may be done in several steps, each bringing the girdle closer to the final shape.
Diamond (gemstone)
A diamond is one of the best-known and most sought-after gemstones...
from a rough stone into a facet
Facet
Facets are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure...
ed gem. Cutting diamond requires specialized knowledge, tools, equipment, and techniques because of its extreme difficulty.
The first guild of diamond cutters and polishers (diamantaire) was formed in 1375 in Nuremberg
Nuremberg
Nuremberg[p] is a city in the German state of Bavaria, in the administrative region of Middle Franconia. Situated on the Pegnitz river and the Rhine–Main–Danube Canal, it is located about north of Munich and is Franconia's largest city. The population is 505,664...
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, and led to the development of various types of 'Cut'. This has two meanings in relation to diamonds. The first is the shape: square, oval, and so on. The second relates to the specific quality of cut within the shape, and the quality and price will vary greatly based on the cut quality. Since diamonds are very hard to cut, special diamond-bladed edges are used to cut them. The first major development in diamond cutting came with the "Point Cut" during the later half of the 14th century: the Point Cut follows the natural shape of an octahedral raw diamond crystal, eliminating some waste in the cutting process.
Diamond cutting, as well as overall processing, is concentrated in a few cities around the world: while 80% of rough diamonds are handled in the Antwerp diamond district
Antwerp diamond district
Antwerp's diamond district, also known as the Diamond Quarter , and dubbed the Square Mile is an area within the city of Antwerp, Belgium. It consists of several square blocks covering an area of about one square mile. Over 12,000 gemcutters and polishers work within the district...
in Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
, more than 50% of processed diamonds also pass through there. 92% of diamond pieces are cut in Surat
Surat
Surat , also known as Suryapur, is the commercial capital city of the Indian state of Gujarat. Surat is India's Eighth most populous city and Ninth-most populous urban agglomeration. It is also administrative capital of Surat district and one of the fastest growing cities in India. The city proper...
, Gujarat state in India. The other important diamond centers are Tel Aviv
Tel Aviv
Tel Aviv , officially Tel Aviv-Yafo , is the second most populous city in Israel, with a population of 404,400 on a land area of . The city is located on the Israeli Mediterranean coastline in west-central Israel. It is the largest and most populous city in the metropolitan area of Gush Dan, with...
and New York city
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
.
Diamond cutting process
The diamond cutting process includes these steps; planning, cleaving or sawing, bruting, polishing, and final inspection.Planning
Diamond manufacturers analyze diamond rough from an economic perspective, with two objectives steering decisions made about how a faceted diamond will be cut. The first objective is that of maximum return on investmentReturn on investment
Return on investment is one way of considering profits in relation to capital invested. Return on assets , return on net assets , return on capital and return on invested capital are similar measures with variations on how “investment” is defined.Marketing not only influences net profits but also...
for the piece of diamond rough. The second is how quickly the finished diamond can be sold. Scanning devices are used to get 3-dimensional computer model of the rough stone. Also, inclusions are photographed and placed on the 3D model, which is then used to find an optimal way to cut the stone.
Maximizing value
The process of maximizing the value of finished diamonds, from a rough diamond into a polished gemstone, is both an art and a science. The choice of cut is influenced by many factors. Market factors include the exponential increase in value of diamonds as weight increases, referred to as weight retention, and the popularity of certain shapes amongst consumers. Physical factors include the original shape of the rough stone, and location of the inclusions and flaws to be eliminated.Weight retention
The weight retention analysis studies the diamond rough to find the best combination of finished stones as it relates to per carat value. For instance, a 2.20 carat (440 mg) octahedron may produce (i) either two half carat (100 mg) diamonds whose combined value may be higher than that of (ii) a 0.80 carat (160 mg) diamond + 0.30 carat (60 mg) diamond that could be cut from the same rough diamond.
The round brilliant cut and square brilliant cuts are preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals, such as macle
Macle
Macle is a term used in crystallography. It is a crystalline form, twin-crystal or double crystal .Macle is an old French word, a heraldic term for a voided lozenge...
s are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight, about 50%. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the weight. Since the per-carat price of a diamond shifts around key milestones (such as 1.00 carat), many one-carat (200 mg) diamonds are the result of compromising Cut quality for Carat weight. Some jewelry experts advise consumers to buy a 0.99 carat (198 mg) diamond for its better price or buy a 1.10 carat (220 mg) diamond for its better cut, avoiding a 1.00 carat (200 mg) diamond, which is more likely to be a poorly cut stone.
Color retention
Natural green color diamonds most often have merely a surface coloration caused by natural irradiation, which does not extend through the stone. For this reason green diamonds are cut with significant portions of the original rough diamond's surface (naturals) left on the finished gem. It is these naturals that provide the color to the diamond.
Turnaround minimization
The other consideration of diamond planning is how quickly a diamond will sell. This consideration is often unique to the type of manufacturer. While a certain cutting plan may yield a better value, a different plan may yield diamonds that will sell sooner, and thereby returning the investment sooner.Cleaving or sawing
Cleaving is the separation of a piece of diamond rough into separate pieces, to be finished as separate gems.Sawing is the use of a diamond saw or laser to cut the diamond rough into separate pieces.
Bruting
Bruting is the process whereby two diamonds are set onto spinning axles turning in opposite directions, which are then set to grind against each other to shape each diamond into a round shape. This can also be known as girdling.Polishing
Polishing is the name given to process whereby the facets are cut onto the diamond and final polishing is performed. The process takes the steps blocking, faceting, also called "brillianteering", and polishing.Final inspection
The final stage involves thoroughly cleaning the diamond in acids, and examining the diamond to see whether it meets the quality standards of the manufacturer.Cutting process
It is possible only because the hardnessMohs scale of mineral hardness
The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in...
of diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
varies widely according to the direction in which one is trying to cut or grind.
A simplified round brilliant cut
Brilliant (diamond cut)
A brilliant is a diamond or other gemstone, cut in a particular form with numerous facets so as to have exceptional brilliance. The shape resembles that of a cone and provides maximized light return through the top of the diamond....
process includes the following stages:
- Sawing the rough stone.
- Table setting where one facet is created. The table facet is then used to attach the stone into a dopDOPDOP may stand for:*Data-oriented parsing*Declaration of Principles, an agreement between Israel and Palestine, also known as the Oslo Accords.*Degree of parallelism*Degree of polarization*Delusions of Parasitosis...
(a lapidaryLapidaryA lapidary is an artist or artisan who forms stone, mineral, gemstones, and other suitably durable materials into decorative items such as engraved gems, including cameos, or cabochons, and faceted designs...
tool holding gemstones for cutting or polishing). - Bruting the girdle.
- Blocking four main pavilion facets.
- Transferring to another dop in order to rotate the stone.
- Blocking four main crown facets.
- Cutting and polishing all pavilion facets.
- Transferring to another dop.
- Cutting and polishing all crown facets.
This is just one, although a fairly common way of creating a round brilliant cut. The actual process also includes many more stages depending on the size and quality of the rough stone. For example, bigger stones are first scanned to get the three-dimensional shape, which is then used to find the optimal usage. The scanning may be repeated after each stage and bruting may be done in several steps, each bringing the girdle closer to the final shape.
External links
- Antique Jewelry University - A History of Diamond Cutting
- Diamond Design, Marcel Tolkowsky. Web edition as edited by Jasper Paulsen.
- History of diamond cutting